How do you calculate soil liquefaction?
2.1 Evaluation of Liquefaction Potential The potential for liquefaction is then described in terms of a factor of safety against liquefaction, FSL = CRR/CSR. If the factor of safety is less than one, i.e., if the loading exceeds the resistance, liquefaction is expected to be triggered.
What is liquefaction PDF?
Liquefaction is the phenomenon when there is loss of strength in saturated and cohesion-less soils because of increased pore water pressures and hence reduced effective stresses due to earthquake loading.
What is CSR and CRR?
The seismic demand of a soil layer represented by Cyclic Stress Ratio (CSR). The capacity of soil to resist liquefaction represented by Cyclic Resistance Ratio (CRR).
What is CRR soil?
cyclic resistance ratio (CRR) of the soil is less than or equal to cyclic stress ratio (CSR) generated by the earthquake, liquefaction is assumed to occur at that location. The factor of safety.
What is liquefaction analysis?
Liquefaction is a phenomenon in which the strength and stiffness of a soil is reduced by earthquake shaking or other rapid loading. It occurs in saturated soils, which are subjected to shaking. The shaking results in the soil particles becoming suspended due to an increase in water pressure.
Is code for liquefaction analysis?
Liquefaction Analysis as Per Is: 1893 (Part-1)-2016 CRR/CSR.
What are the types of soil liquefaction?
3. Types of Soil Liquefaction
| Flow liquefaction | Cyclic Softening | |
|---|---|---|
| Soil Types | Any metastable saturated soil; very loose granular deposits, very sensitive clays, and loess deposits | Almost all saturated sands, with limited deformations in clayey soils. |
What causes liquefaction?
Liquefaction takes place when loosely packed, water-logged sediments at or near the ground surface lose their strength in response to strong ground shaking. Liquefaction occurring beneath buildings and other structures can cause major damage during earthquakes.
What is liquefaction potential index?
Liquefaction potential index (LPI), originally proposed by Iwasaki et al. (1982), is frequently used to evaluate the liquefaction potential of soils. LPI is proportional to the thickness of liquefiable and non-liquefiable soil layers as well as the value of the factor of safety against soil liquefaction.
How is corrected SPT N value calculated?
19.5. 6 How to obtain (N1) Nm, SPT value measured in the field. CN, overburden correction factor = (Pa/σ′)0.5Pa = 100 kPa; σ′, effective stress of soil at point of measurement.
What is soil liquefaction and how does it occur?
Soil liquefaction is the tendency of saturated soil to become a suspension when subjected to extreme vibrations, primarily due to tectonic activity. Soil liquefaction is a major cause of damage to structures when it occurs. An example of soil liquefaction occurring is Loma Prieta, California, Earthquake on October 17, 1989.
What is the computational model for soil liquefaction?
Our computational model is based on equations taken from Technical Report Seismic Design Criteria for Soil Liquefaction by the Naval Facilities Engineering Service Center. The equation we are using to find the determine if Soil Liquefaction will occur: FS = CSRL/CSRE FS stands for the safety factor against soil liquefaction occurring.
What happens to pore water pressure during liquefaction of soil?
As shown in the figure 14, there is a sudden build up of pore water pressure in the first cycle it self and there after increases steadily. The 100% pore pressure ratio occurs in 10th cycle at which the deviator stress reduces to zero indicating the stage of liquefaction of soil.
How to evaluate the liquefaction resistance of the in situ soil?
Figure 6 presents a chart for evaluating the liquefaction resistance of the in situ soil based on the measured shear wave velocity of the soil. The shear wave velocity can be measured in situ employing different geophysical techniques, such as the uphole, down-hole, or cross-hole methods. Here, vs1 represents the corrected shear wave velocity.